Patent GB-1001284-A (GB)
Title: Improvements in or relating to the sulphonation of fatty acid esters
IPC: C07C309/62
Filed: 1962-08-02
Abstract: Esters of fatty acids with 6-28 carbon atoms in their molecules with polyhydric alcohols, which esters have no sulphatable or sulphonatable groups other than a hydrogen atom on the a -carbon atom and which have an iodine value below 5 are sulphonated by treating them with excess amounts of gaseous sulphur trioxide, not combined in the form of an adduct, and in admixture with fatty acids with 6-28 carbon atoms in their molecules, and with an iodine value of below 5, or their nitriles or esters with monohydric alcohols of at most 20 and preferably less than 18 carbon atoms, and especially of up to 5 carbon atoms, provided that these derivatives have an iodine value below 5. Preferably natural triglycerides are used but synthetic triglycerides or esters of fatty acids with other polyols, e.g. glycols, pentaerythritol, mannitol and sorbitol, may be used. Preferably the fatty acids have 8-18 carbon atoms in their molecules, e.g. those derived from natural fats.  Sulphonation products soluble at low temperatures, e.g. 20-45 DEG  C., are made from fats derived from acids of 10-14 carbon atoms in their molecules and especially lauric acid, and products usable at 50-100 DEG  C. are obtained from fats derived from acids of 16-18 carbon atoms per molecule, e.g. hydrogenated vegetable fats and hydrogenated tallow, whale or fish oils.  Monohydric alcohols indicated are methyl to nonyl alcohols and monohydric alcohols obtained synthetically by e.g. the reduction of fatty acids or fatty acid mixtures.  The hydrogenation products of oleyl oleate or natural, or synthetic, wax esters may also be used as esters of monohydric alcohols.  Preferred are esters of primary or secondary monohydric alcohols of 1-5 carbon atoms.  Impurities in the starting materials which lead to strongly coloured products should preferably be removed before sulphonation as by e.g. hydrogenating to an iodine value of below 2.  The fatty acids, or their derivatives, should preferably be distilled before sulphonation.  If, because of liability to decomposition, distillation is not possible impurities, such as proteins and mucins, should be separated during the deacidification and refining of the oils.  Generally at least 10-85%, preferably 20-75%, of fatty acid, or derivative thereof, is used by weight of total starting material.  Sulphonation may be effected continuously, or discontinuously, the sulphur trioxide used being diluted with a gas such as air, nitrogen or carbon dioxide, the content of trioxide being 2-40, preferably 3-20% by volume. 1.1-1.8, preferably 1.2-1.6, moles of trioxide should be used per mole of fatty acid residue while larger quantities of sulphonating agent must be used with increasing length of the fatty acid, and alcohol residue, if high degrees of sulphonation are to be obtained.  High degrees of sulphonation are obtained at 70-100 DEG  C, preferably 75-95 DEG  C, especially 80-90 DEG  C.  Advisably the reaction mixture is kept at the final temperature for the shortest time possible.  To minimize the formation of highly coloured products the sulphonation processes of Specified 999,300 and 1,001,286 may be used.  The products contain excess sulphur trioxide which may be removed as in Specification 1,001,285 by treatment with alcohols to produce surface-active agents, and when this treatment is envisaged up to 2 or 3 mols of sulphur trioxide per mol of fatty acid residue in the starting-material, may be used in the sulphonation reaction. The products may be bleached by the process of Specification 1,001,283.  The products may be neutralized in conventional fashion with inorganic or organic bases and any sulpho-fatty acids obtained may be neutralized to give monosalts which may be esterified with hydroxy compounds. Examples are provided of the sulphonation process in which the polyol esters used are hydrogenated coconut oil and tallow and the additional reagents used are the ethyl esters of hydrogenated coconut oil, palm kernel oil and tallow fatty acids, and a mixture of the ethyl or methyl esters of the two latter acids.